Nobody likes when you don't get to pick your own lab partner. Especially, when you get paired with the quiet kid.
Harry isn't popular, but he has the most tight group of friends in the world; Zayn, Liam, and Niall.
Louis, on the other hand, has no friends. He doesn't really talk either, he's the quiet kid/the outcast. What could add to this is the fact that - well - he doesn't talk. Not that he can't, he just has been trained not too. No one truly knows why, however, the bruises on his body do give some clues.